If you want to get Product id from order id in Woocommerce then fetch order details.

$order = new WC_Order( $order_id );
$items = $order->get_items();

then if you loop through them, you can get all the relevant data:

foreach ( $items as $item ) {
    $product_name = $item['name'];
    $product_id = $item['product_id'];
    $product_variation_id = $item['variation_id'];
}

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If you want to get list of all woocommerce orders by date then using below code. Here change the value of $your_date by yourself.
Assign particular date to $your_date. This code will return the list of woocommerce orders placed in a particular date.

	$your_date = '2016-09-23';
	$args = array(
			'post_type' => 'shop_order',
			'post_status' => 'publish',
			'posts_per_page' => -1,
			'date_query'=> array(
					'after' => $your_date,
					'inclusive' => true,
					)
		);
	$orders = get_posts($args);

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If you want to set blog page programmatically in WordPress then add that following code in your functions.php file. First you have to make sure that blog page is exists or not. if its no exists then create it. After that add that following code in your functions.php file

$blog   = get_page_by_title( 'Blog' );
update_option( 'page_for_posts', $blog->ID );

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If you want to set front page programmatically in WordPress then add that following code in your functions.php file. First you have to make sure that front page is exists or not. if its no exists then create it. After that add that following code in your functions.php file

$home = get_page_by_title( 'Home' );
update_option( 'page_on_front', $home->ID );
update_option( 'show_on_front', 'page' );

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For our customization want to completely disable all types of automatic updates, core or otherwise, add the following to your wp-config.php file

define( 'AUTOMATIC_UPDATER_DISABLED', true );

This code will completely disable all types of automatic updates.

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There is no hooks available to change payment method label in woocommerce checkout page. You can change this label by use your woocommerce checkout settings.

For example
http://www.boopathirajan.com/wp-admin/admin.php?page=wc-settings&tab=checkout

Here replace http://www.boopathirajan.com instead of your web site name.

Reserved terms are the set of key words in a WordPress. You should avoid this terms in your plugin or theme files. Because it leads to conflict with core functionality. So don’t use this reserved terms in following places.

1. Passing a term through a $_GET or $_POST array
2. Registering a taxonomy or post type slug
3. Handling query variables

To learn more about WordPress reserved terms, please see http://codex.wordpress.org/Function_Reference/register_taxonomy#Reserved_Terms

For our customization want to disable post revisions completely from WordPress then do the following:
Open wp-config.php file which is located in your website root folder. Add following code in that file.

define ('WP_POST_REVISIONS', false);

if you have any doubt, then comment here!

For our customization want to limit the maximum number of post revisions then do the following:
Open wp-config.php file which is located in your website root folder. Add following code in that file.

define ('WP_POST_REVISIONS', 5);

Here 5 is an post revision limit. you can alter this value as you want. if you have any doubt, then comment here!

When you register custom post type, you have to add support for revisions. Title and text editor is the default support. if you want to enable revisions for your custom post type then you have to add like this.

'supports' => array( 'title', 'editor', 'revisions' ),

Add this code in your custom post type creation arguments array. for your information i listed available supports below.

1.'title'
2.'editor' 
3.'author'
4.'thumbnail' 
5.'excerpt'
6.'trackbacks'
7.'custom-fields'
8.'comments' 
9.'revisions' 
10.'page-attributes' 
11.'post-formats'

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